A Manhattan man who biked to the World Trade Center in a desperate bid to try and save his aunt is among the thousands missing.

Isaac Rivera, 19, of Manhattan, was watching TV in his apartment when he heard about the disaster at the Twin Towers.

He hopped on his bike and rushed over to the scene to see if he could help lead the beloved relative out of the building.

His mother, Gloria Rivera of Queens, said, “when he saw the news, he thought of my sister who works there.”

“He went running to see if he could find her and he never came back,” she said. Within a few hours, the sister called Gloria.

“She’s fine,” Gloria said. “She called us. She’s fine.”

Gloria and Isaac’s fiancee, Leslie Outten, 18, spent the day yesterday going from hospital to hospital, praying they’d find Isaac and he’d be fine too, but his name didn’t appear on any of the list of injured.

“He went to see if she was OK and we haven’t heard from him,” Outten cried. “Nothing.”